1. Field of the Invention
The invention relates to a broadband communications antenna having a baseplate which has a conductive layer having at least one coupling opening, with a stripline network being provided at a short distance from the conductive layer in the region of the coupling openings, with at least one conductive patch being arranged opposite the baseplate, with the baseplate and the patch being arranged in a conductive housing which has one open side, and with the baseplate being arranged closest to the housing bottom and thus furthest away from the open side.
A broadband antenna such as this is known from a report on the Ecole Polytechnique Fxc3xa9dxc3xa9rale de Lausanne, which was published under the title xe2x80x9cSSAIP: A Cavity Backed Alternative to Broadband Communication Antennasxe2x80x9d.
2. Description of the Prior Art
Microstrip antennas are known per se, and are in widespread use. Their field of operation is restricted by their narrow bandwidth, which is a result of their resonant structure. The use of thick substrates and a number of layers to increase the bandwidth leads to a reduction in the radiation efficiency of the antennas. The prior art mentioned above proposes an antenna which has a physical height of 30 millimeters for a frequency of approximately 6 Gigahertz.
A new mobile radio standard entitled UMTS (Universal Mobile Telecommunications System) has been defined with frequencies in the band between 1920 and 2170 Megahertz. The existing GSM 1800 network is located in the frequency band between 1710 and 1880 Megahertz. It would now be desirable to specify a broadband antenna which can cover both frequency bands. The prior art is not suitable for this purpose, either in terms of its respective power levels for the two bands or in terms of its technical design, since the antenna has a physical height of more than 70 mm in this frequency band. The prior art provides a bandwidth of approximately 25% for matching with 10 dB, while in contrast a band width of more than 30% would be desirable.
Against the background of this prior art, the invention is based on the object of improving an antenna of the type mentioned initially such that this antenna allows integration of a GSM network and the UMTS network by means of a single antenna, with losses that are as low as possible.
This object is achieved in that one or more lugs are provided on the open side of the housing and reduce the size of the open cross-sectional area of the housing in a plan view of the open side.
The provision of lugs which reduce the size of the open cross section of the antenna housing allows a major increase in the bandwidth to be achieved while, in contrast, the prior art would have to increase the size of the open cross section of the antenna housing.